Large deployable antenna program. Phase 1: Technology assessment and mission architecture

The program was initiated to investigate the availability of critical large deployable antenna technologies which would enable microwave remote sensing missions from geostationary orbits as required for Mission to Planet Earth. Program goals for the large antenna were: 40-meter diameter, offset-fed paraboloid, and surface precision of 0.1 mm rms. Phase 1 goals were: to review the state-of-the-art for large, precise, wide-scanning radiometers up to 60 GHz; to assess critical technologies necessary for selected concepts; to develop mission architecture for these concepts; and to evaluate generic technologies to support the large deployable reflectors necessary for these missions. Selected results of the study show that deployable reflectors using furlable segments are limited by surface precision goals to 12 meters in diameter, current launch vehicles can place in geostationary only a 20-meter class antenna, and conceptual designs using stiff reflectors are possible with areal densities of 2.4 deg/sq m

COBE On-Orbit Engineering Performance, volume 1

The Cosmic Background Explorer (COBE) was successfully launched on Nov. 18, 1989. The Delta Launch Vehicle performed flawlessly, and observatory deployments occurred as planned. The dewar cover successfully deployed on day 4, as planned, and the cryogen temperature is currently at 1.41 K. All three instruments are operating and acquiring science data, and the Payload Operational Control Center (POCC)/Network support has been excellent. Various performance aspects of the COBE are presented in view graph form

Large Space Antenna Systems Technology, part 1

A compilation of the unclassified papers presented at the NASA Conference on Large Space Antenna Systems Technology covers the following areas: systems, structures technology, control technology, electromagnetics, and space flight test and evaluation

Space Mechanisms Lessons Learned Study. Volume 2: Literature Review

Hundreds of satellites have been launched to date. Some have operated extremely well and others have not. In order to learn from past operating experiences, a study was conducted to determine the conditions under which space mechanisms (mechanically moving components) have previously worked or failed. The study consisted of an extensive literature review that included both government contractor reports and technical journals, communication and visits (when necessary) to the various NASA and DOD centers and their designated contractors (this included contact with project managers of current and prior NASA satellite programs as well as their industry counterparts), requests for unpublished information to NASA and industry, and a mail survey designed to acquire specific mechanism experience. The information obtained has been organized into two volumes. Volume 1 provides a summary of the lesson learned, the results of a needs analysis, responses to the mail survey, a listing of experts, a description of some available facilities, and a compilation of references. Volume 2 contains a compilation of the literature review synopsis

The 29th Aerospace Mechanisms Symposium

The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft

System Design of the Miniaturized Distributed Occulter/Telescope (mDOT) Science Mission

The miniaturized Distributed Occulter Telescope (mDOT) will provide unprecedented detection and direct measurements of brightness of extrasolar dust disks at short visible to ultraviolet wavelengths. The baseline mission will observe over 15 targets using a starshade for high-contrast imaging, blocking the target star with a specially shaped free-flying occulter to allow nearby objects to be detected. mDOT operates on a much smaller scale than flagship NASA missions, with an autonomous formation of two small satellites in sun-synchronous low Earth orbit. An occulter-smallsat (246kg, 192W) carries a precisely manufactured 3m-diameter starshade and a telescope-cubesat (6U, 12kg, 40W) carries a 10cm-diameter telescope. The satellites are launched combined as a secondary payload for a total mission lifetime of 1.1 years. After launch, the occulter-smallsat ejects the telescope-cubesat and maneuvers to establish the desired relative orbit, leaving the spacecraft at slightly different longitudes of ascending node. Relative eccentricity and inclination vector separation provides the baseline for scientific observations at the equator (500 km) and a minimum safe distance perpendicular to the flight direction at all times (\u3e1km). The starshade suppresses the light of the target star by 10-7 or more. During a science pass, high-ISP green propellant thrusters on the occulter-smallsat maintain the formation, while differential GNSS is used for cm-accurate relative navigation. Earth’s oblateness perturbations are used to precess the orbits and acquire the science targets over the mission lifetime at minimal propellant cost. The mission addresses key NASA science objectives and provide the unique opportunity to mature starshade techniques for future exoplanet missions

Activities of the Center for Space Construction

The Center for Space Construction (CSC) at the University of Colorado at Boulder is one of eight University Space Engineering Research Centers established by NASA in 1988. The mission of the center is to conduct research into space technology and to directly contribute to space engineering education. The center reports to the Department of Aerospace Engineering Sciences and resides in the College of Engineering and Applied Science. The college has a long and successful track record of cultivating multi-disciplinary research and education programs. The Center for Space Construction is prominent evidence of this record. At the inception of CSC, the center was primarily founded on the need for research on in-space construction of large space systems like space stations and interplanetary space vehicles. The scope of CSC's research has now evolved to include the design and construction of all spacecraft, large and small. Within this broadened scope, our research projects seek to impact the underlying technological basis for such spacecraft as remote sensing satellites, communication satellites, and other special purpose spacecraft, as well as the technological basis for large space platforms. The center's research focuses on three areas: spacecraft structures, spacecraft operations and control, and regolith and surface systems. In the area of spacecraft structures, our current emphasis is on concepts and modeling of deployable structures, analysis of inflatable structures, structural damage detection algorithms, and composite materials for lightweight structures. In the area of spacecraft operations and control, we are continuing our previous efforts in process control of in-orbit structural assembly. In addition, we have begun two new efforts in formal approach to spacecraft flight software systems design and adaptive attitude control systems. In the area of regolith and surface systems, we are continuing the work of characterizing the physical properties of lunar regolith, and we are at work on a project on path planning for planetary surface rovers

Conceptual design and analysis of a large antenna utilizing electrostatic membrane management

Conceptual designs and associated technologies for deployment 100 m class radiometer antennas were developed. An electrostatically suspended and controlled membrane mirror and the supporting structure are discussed. The integrated spacecraft including STS cargo bay stowage and development were analyzed. An antenna performance evaluation was performed as a measure of the quality of the membrane/spacecraft when used as a radiometer in the 1 GHz to 5 GHz region. Several related LSS structural dynamic models differing by their stiffness property (and therefore, lowest modal frequencies) are reported. Control system whose complexity varies inversely with increasing modal frequency regimes are also reported. Interactive computer-aided-design software is discussed

33rd Aerospace Mechanisms Symposium

The proceedings of the 33rd Aerospace Mechanisms Symposium are reported. JPL hosted the conference, which was held at the Pasadena Conference and Exhibition Center, Pasadena, California, on May 19-21, 1999. Lockheed Martin Missiles and Space cosponsored the symposium. Technology areas covered include bearings and tribology; pointing, solar array and deployment mechanisms; orbiter/space station; and other mechanisms for spacecraft

Orbiting deep space relay station study. Volume 2: Conceptual design

The Orbiting Deep Space Relay Station conceptual design is described. The baseline for implementation cost and schedule estimates is also described